The description of my truck is in my sig. It started weeping coolant down the side of the engine right by the thermostat housing (common problem I've found out). Now it just plain gushes, so it's time to take it apart. I'm going to have the head milled and a valve job done. What head gasket do I use to put it back together? Do I need to use a thicker one since the head is getting cut? Do I need head studs or can I reuse the bolts? Some day in the future I might swap the turbo for something with a larger turbine housing, but I don't have any more big mods planned. I'm happy with the power the way it is, just want to try to drop the EGT a bit. So, can I get away with stock parts or would it be smart to upgrade while I'm in there?

 

Cummins has a stretch gauge to check your bolts, should be in with the HG. You won't change anything by planing the head, the combustion chamber is in the piston, head is flat.

I would go stock.

 

I just did the same thing and went with a stock Cummins hg. However, it really depends on how much they take off the head to make it flat, if any.

Cummins headgasket part numbers are as follows (same as marine):

3283335 is the standard thickness
3283337 is the .010" thicker
3283339 is the .020" thicker

I would just get new bolts... Or studs.


Some additional part numbers you might need that I've gathered:

-Large intake manifold gasket (rectangle), Cummins:
3938152

-Small heater grid gasket (square), Cummins:
3969988

-Valves, Cummins:
Intake: 3802355
Exhaust: 3802356

Valve Springs, Cummins (intake & exhaust same part #):
36 psi: 3926700 (Stock Dodge application for my engine serial #56235536)) - $3.61/each
60 psi: 3916691 (Dodge w/ exhaust brake) - $11.16/each

 

Nope, the only time your compression will change is if you deck the block.

The head is flat as a pancake........

 

Really? I've never seen one apart before but I figured there'd have to be at least some kind of chamber in the head. So then, does it screw up the valve job if the head has to be milled flat?

 

They will usually redo the valves when it is apart.

 

Ok. So it sounds like stock parts will work. I just want to make double sure though - I'm at about 38 psi and 15.5*.

 

Ok, here's another thought... I'm getting a valve job done after the head is milled. So, if .010 is taken off the head and the valves are sunk .010, the net change in the distance from the piston to valve is zero. Now, does it make any difference if the injector is .010 closer? If so, then I can see why I'd want a +.010 gasket. On the downside here, a thicker gasket lowers the compression ratio. Anyone have any input here?

 

The Cummins tech told me to go with a 10 over because the injector tip might hit the piston (0.008" off the head in my case), however I spoke to Richard at Browns Diesel who does articles for Diesel Power and he said not to worry about it. He said I could go either way but recommended the stock gasket. In fact, he said I should even use the thinnest copper washers for the injectors. That's what I'm running now.

If 0.010 is taken off the valves then that'll compensate for the 0.010 lost on the head. If the valves were not machined AND 0.010 was taken off the head, then that's when you need to go with a 0.010 over. That's what I meant in my earlier post.